• Journal of the Korean Institute of Educational Facilities
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• v.24 no.2
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• pp.11-18
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• 2017

Most primary and secondary schools in Korea provide school meals to students. After the implementation of the manual in the development of foodservice facilities within schools in the Seoul metropolitan area, this study had been instituted towards the improvement on the design of the school. Through the investigation of the use of school foodservice facilities and the establishment of putting the designer's design to the users into effect, primary and secondary schools have been observed in the study to conclude the following research: Spatial Configuration and Usage Characteristics within Elementary, Middle, and High school.

• Journal of information and communication convergence engineering
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• v.11 no.4
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• pp.223-228
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• 2013

Cognitive radio has been recently considered a promising technology to improve spectrum utilization by enabling secondary access to licensed bands that are not used by primary users temporarily or spatially. A prerequisite to this secondary access is the lack of interference to the primary system. This requirement makes spectrum sensing a key process for cognitive radio. In this study, we consider amplify and forward (AF)-based cooperative spectrum sensing for cognitive radio networks where multiple relay nodes are utilized to amplify and forward the primary user signal for better spectrum sensing, and maximum ratio combining is used for fusion detection by a cognitive coordinator. Further, the detection probability and the bit error rate of AF-based cooperative spectrum sensing are analyzed in fading multiple cognitive relay channels. The simulation results show that the AF-based cooperative spectrum sensing scheme outperforms the conventional scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.597-598
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• 2011

In this paper, the spectrum hole prediction scheme was proposed for the cognitive radio networks using the primary user's traffic pattern. Using the channel prediction, the collision probability with primary users can be reduced and the system throuthput can be improved. Simulation result shows that the proposed method can enhance the throughput and reduce the interference to the primary user below the desired threshold.

• Journal of Korea Entertainment Industry Association
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• v.5 no.2
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• pp.77-86
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• 2011

This paper is aimed at analyzing the relationship between users' actions in relation to a SNG (Social Network Game), which mainly targets communities, and the motivations that give rise to such selective actions. The subjects of existing researches on game area have rarely dealt with game users but mainly focused on the studies and utilization of game production technologies; and, in cases of studies on games users, their subjects have been hardly more than observations of users' behaviors in relation to the performance to achieve certain goals or themes of a game; for example, upgrading a character's level or obtaining rewards through "defeat". Therefore, it is necessary to analyze the actions of SNS game users from the perspective of behavioral selections caused by various motivations of human beings rather than approaching from the perspective of problem solving methods. In order to accomplish this goal, fist of all, Lazzaro's People Fun model and motivation theory of SNS users will be analyzed. Secondly, relevant materials from 13 SNG cases will be collected. Games' events and the functional actions of users will be classified. Lastly, the primary actions of SNG users will be classified into 8 different types and motivations - action patterns will be analyzed based on the classified materials.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.8
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• pp.877-889
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• 2016

In this paper, we introduce the basic components of the Cognitive Radio Networks along with possible threats. Specifically, we investigate the SSDF (Spectrum Sensing Data Falsification) attack which is one of the easiest attack to carry out. Despite its simplicity, the SSDF attack needs careful attention in order to build a secure system that resists to it. The proposed scheme utilizes the Anomaly Detection technique to identify malicious users as well as their sensing reports. The simulation results shows that the proposed scheme can effectively detect erroneous sensing reports and thus result in correct detection of the active primary users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.3
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• pp.249-257
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• 2013

Recently, data traffic is significantly increased by high rate data service. As a result, radio spectrum is considered one of the most scarce and valuable resources for wireless communications. For the solution of this problem, cognitive radio(CR) has been proposed as an efficient means to opportunistic spectrum sharing between primary (licensed) users and cognitive radio users. In this paper, user selection scheme in CR networks is proposed for additional consideration of secondary system. The proposed user selection scheme mitigates interference to primary user by using orthogonal channel vectors while improves performance of secondary system. Simulation results show that the proposed scheme achieves 1.62bps/Hz higher average throughput of whole system than one of the existing scheme.

• Journal of Distribution Science
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• v.17 no.12
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• pp.55-62
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• 2019

Purpose: The number intelligent homecare products are focused on the development of technology, resulting in a lack of realistic environments or requirements for consumers. The purpose of this paper is to define the consumer and context for intelligent homecare products and to develop a usability evaluation scale. Research design, data and methodology: For this study, first, consumer and contexts related to intelligent homecare products were analyzed through literature review. Second, the primary usability evaluation factors were derived for intelligent homecare products by collecting the factors related to usability evaluation and conducting in-depth interviews with experts. Third, the second usability evaluation factors were derived through survey and statistical analysis based on the derived usability evaluation factors. Results: As a result, users of intelligent homecare products were classified as primary users and secondary consumers and six related contexts. The usability evaluation scale was established with four factors - Functionality, Error, Convenience, and Emotion - and 13 items. Conclusions: This study can be the basis for developing and distributing products that meet the consumer environment and requirements related to intelligent homecare products that will contribute to securing the competitiveness of companies and developing the technology and service value of related industries.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.112-122
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• 2016

Cognitive radio (CR) is considered an attractive technology to deal with the spectrum scarcity problem. Multi-radio access technology (multi-RAT) can improve network capacity because data are transmitted by multiple RANs (radio access networks) concurrently. Thus, multi-RAT embedded in a cognitive radio network (CRN) is a promising paradigm for developing spectrum efficiency and network capacity in future wireless networks. In this study, we consider a new CRN model in which the primary user networks consist of heterogeneous primary users (PUs). Specifically, we focus on the energy-efficient resource allocation (EERA) problem for CR users with a special location coverage overlapping region in which heterogeneous PUs operate simultaneously via multi-RAT. We propose a two-tier crossover genetic algorithm-based search scheme to obtain an optimal solution in terms of the power and bandwidth. In addition, we introduce a radio environment map to manage the resource allocation and network synchronization. The simulation results show the proposed algorithm is stable and has faster convergence. Our proposal can significantly increase the energy efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.18-34
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• 2014

It is widely believed that cognitive radio (CR) networks have an opportunistic nature and therefore can only support best-effort traffics without quality-of-service (QoS) guarantees. In this paper, we propose a centralized CR network that adopts interference averaging techniques to support QoS guaranteed traffics under interference outage constraints. In such a CR network, a CR user adaptively adjusts its transmit power to compensate for the channel loss, thereby keeping the receive signal power at the CR base station (BS) at a constant level. The closed-form system capacity of such a CR network is analyzed and derived for a single cell with one CR BS and multiple CR users, taking into account various key factors such as interference outage constraints, channel fading, cell radius, and locations of primary users. The accuracy of the theoretical results is validated by Monte Carlo simulations. Numerical and simulation results show promising capacity potential for deploying QoS-guaranteed CR networks in frequency bands with fixed primary receivers. Our work can provide theoretical guidelines for the strategic planning of centralized CR networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.243-246
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• 2019

In cognitive radio networks, secondary transmitters should cease its transmission immediately under the detection of primary transmission in the spectrum they are using. Then they need to exploit another idle spectrums and resynchronize to the newly found idle spectrums. Most of related work presume the existence of separate control channel used by secondary users commonly for exchanging the information of idle spectrums. However, this presumption is not feasible in real world cognitive radio scenario. Therefore we address a proactive spectrum synchronization scheme with no need of separate control channel. Our scheme lets secondary users exchange the spectrum information periodically during normal communication process and determine the next spectrum band in advance of detecting primary transmission. We evaluate our scheme in a real world cognitive radio environments set up with USRPs.